1. Field of the Invention
This invention relates generally to robot arm systems and, more particularly, to robotic arm pick-and-place mechanisms.
2. Related Art
Robotic storage libraries for computer data have been designed to provide automated dam storage and retrieval at a reasonable cost. One of the characteristics of the storage library which affect this overall cost is storage capacity; that is, dollars per gigabytes stored. The storage capacity is influenced by the size of the media storage device, robotic hardware, and electrical support devices. One of the more considerable contributors to the overall storage capacity is the size of the operating envelope of the pick-and-place mechanism used to retrieve and replace the objects, typically computer tape cartridges, from the their stored position. This is because the pick-and-place mechanism is essentially added to the volume of each media storage device since the pick-and-place mechanism must be swept through its path of travel and be positioned to access each storage cell position.
Conventional robotic pick-and-place mechanisms have utilized a gripper mechanism to grab onto the magnetic tape cartridge, and a slider mechanism to convey the gripped magnetic tape cartridge into or out of the pick-and-place mechanism. This configuration requires a large operating envelope due to the use of two separate mechanisms, the gripper mechanism and the slider mechanism, to retrieve and replace the magnetic tape cartridge, with each having an associated servo system to control the motions of the mechanism. This results in a pick-and-place mechanism having a large design envelope which impacts the storage density of the storage library. Typically, the storage density of storage library systems using conventional pick-and-place mechanisms is approximately 63 cartridges per square foot.
What is needed is a robotic pick-and-place mechanism which has a minimal operating envelope, thereby increasing the overall storage density of the storage library. The size of this operating envelope is dependent upon the size of the object that the robotic pick-and-place mechanism is designed to retrieve and deposit. Since the magnetic tape cartridge will require a certain amount of area in order to be properly positioned for placement in a target device, the ideal robotic pick-and-place mechanism will have an operating envelope the same as or smaller than this area.
The robotic pick-and-place mechanism must be configured to adapt easily to presently available robotic arm assemblies. In addition, the reduced size and operating envelope of the robotic pick-and-place mechanism must not interfere with the accuracy, speed, or other functional capabilities of the pick-and-place mechanism.